<template>
  <div>
    <canvas id ="canvas"
            :style="{width: width + 'px', height: height + 'px'}"
            @click = "refreshCanvas"/>
  </div>
</template>

<script>
export default {
  name: "CanvasCode",
  props: {
    width: {
      type: Number,
      default: 100
    },
    height: {
      type: Number,
      default: 50
    },
    numLen: { // 验证码数字多少
      type: Number,
      default: 4
    },
    lineLen: {  // 线段数量
      type: Number,
      default: 4
    },
    dotLen: {  // 点的数量
      type: Number,
      default: 30
    },
    angle: {  // 随机倾斜角度
      type: Number,
      default: 30
    }
  },
  data()
  {
    return {
      codeArr: [],
      trueCode: ""
    }
  },
  mounted() {
    this.refreshCanvas();
  },
  methods: {
    refreshCanvas()
    {
      this.draw(this.codeArr);
    },
    draw(showNum)
    {
      let canvas_width = document.querySelector("#canvas").clientWidth;
      let canvas_height = document.querySelector("#canvas").clientHeight;
      let canvas = document.getElementById("canvas"); // 获取到canvas
      let context = canvas.getContext("2d"); // 获取到canvas画图
      canvas.width = canvas_width;
      canvas.height = canvas_height;
      let sCode =
          "1,2,3,4,5,6,7,8,9,0";
      let aCode = sCode.split(",");
      let aLength = aCode.length; // 获取到数组的长度

      // 4个验证码数
      for (let i = 0; i <= this.numLen - 1; i++)
      {
        let j = Math.floor(Math.random() * aLength); // 获取到随机的索引值
        let deg = Math.random() * this.angle * Math.PI / 180; // 产生0~30之间的随机弧度
        let txt = aCode[j]; // 得到随机的一个内容
        showNum[i] = txt; // 依次把取得的内容放到数组里面
        let x = (this.width / 10) + i * (this.width / this.numLen - 5); // 文字在canvas上的x坐标
        let y = (this.height * 0.6)  + Math.random() * 8; // 文字在canvas上的y坐标
        context.font = `bold ${this.width / this.numLen + "px"} 微软雅黑`;

        context.translate(x, y);
        context.rotate(deg);

        context.fillStyle = this.randomColor();
        context.fillText(txt, 0, 0);

        context.rotate(-deg);
        context.translate(-x, -y);
      }
      // 验证码上显示6条线条
      for (let i = 0; i <= this.lineLen - 1; i++)
      {
        context.strokeStyle = this.randomColor();
        context.beginPath();
        context.moveTo(
            Math.random() * canvas_width,
            Math.random() * canvas_height
        );
        context.lineTo(
            Math.random() * canvas_width,
            Math.random() * canvas_height
        );
        context.stroke();
      }
      // 验证码上显示30个小点
      for (let i = 0; i <= this.dotLen - 1; i++)
      {
        context.strokeStyle = this.randomColor();
        context.beginPath();
        let x = Math.random() * canvas_width;
        let y = Math.random() * canvas_height;
        context.moveTo(x, y);
        context.lineTo(x + 1, y + 1);
        context.stroke();
      }

      // 最后把取得的验证码数组存起来，方式不唯一
      let num = showNum.join("");
      this.trueCode = num.toLowerCase();
      this.$emit("currentCode", this.trueCode);
    },
    // 得到随机的颜色值
    randomColor()
    {
      let r = Math.floor(Math.random() * 256);
      let g = Math.floor(Math.random() * 256);
      let b = Math.floor(Math.random() * 256);
      return "rgb(" + r + "," + g + "," + b + ")";
    },
    // 验证对不对
    verifyCode(inputCode)
    {
      return inputCode === this.trueCode;
    }
  }
}
</script>

<style scoped>
#canvas{
  cursor: pointer;
}
</style>
